Technical Abstract:
Stable C isotopes provided a unique method of tracing C movement through individual compenents of a shortgrass steppe ecosystem. Analyses enabled us to assign estimates for C pools and fluxes which were otherwise difficult to measure directly, and therefore allowed us to constrain estimates of net ecosystem production. Based on measurements made in our study on the shortgrass steppe, we found that elevated CO2 stimulated not only plant productivity but also rhizodeposition and decomposition fluxes, thus resulting in no overall differences in net ecosystem production between ambient and elevated CO2 during a moist growing season.